CF Genes and Siblings

[anonymous]

My question will be short but the answer I'm afraid may only be known by a few. So anyhelp would be appreciated.

My daughter will be having the Sweat Chloride test next week. It would have been tomorrow but she had a bit of an ear infection flare up over the weekend. Her Mom and I are very anxious to know what the status is.

Neither my wife nor I was screened prior to birth or since. We are just being educated on CF and how it "works". My question is this ... although I wasn't tested my biological sister was and she was negative, would this mean that I am not a carrier either or is that inconclusive??

Any help with this answer would be greatly appreciated.

 

[Emily65Roses]

Inconclusive. If both of your parents carry the CF gene, you have 3 possible outcomes for the children (i.e. you and your sister): 25% the child will have CF, 50% they will be a carrier, and 25% they won't have CF or carry it.

As for my family, I have CF. My full biological sister doesn't even carry it. So we got either 25% extreme. It's very possible that your sister is the in 25% that don't carry it, and you landed in the 50% that do category.

As for your daughter, the sweat test is becoming obsolete almost. A lot of them are done wrong, read wrong, etc. A more conclusive accurate test would be a blood test where they check for the genes, like they do with carriers. Plus, that way you can find out WHICH specific genes she has (there are more than 1,000, I believe), and that may make a difference in her care.

Any other questions, feel free to ask.

 

[becca23]

Is there is a family history of cf? Yes there is a possibility that you could be a arrier and your sister is not.

 

[anonymous]

no ... our family has no history of CF. is that a good sign or inconclusive as well? from what Emily stated I would think that is a positive sign for me not haivin the gene.

 

[Emily65Roses]

Oh and one more thing, after Becca's comment. This is not to say you're wrong or anything, Becca. Of course not. But I should make it known... if you have no family history, it's very possible that doesn't mean anything. My mom was one of 6, I have more than a dozen cousins, something like 10 aunts and uncles, and I am the <b>first and only</b> one with CF. Just a word to the wise. <img src="i/expressions/face-icon-small-smile.gif" border="0"> And my kind of situation isn't uncommon. There are many here who are the only CFers in their family. Kay I'm done now. Haha.

Feel free to keep asking. <img src="i/expressions/face-icon-small-smile.gif" border="0">

 

[becca23]

I was jsut wondering if there was a history of cf, I typed the wrong word.

 

[Emily65Roses]

No, it's still a valid question. Sometimes it can give you a hint. If there's a history, it tends to be more possible that the person in question has CF.

I just had to point out that a lot of people take that to mean no family history must mean it's more possible that the person in question does NOT have CF, and that's not really the case. <img src="i/expressions/face-icon-small-smile.gif" border="0">

 

[anonymous]

This is great information. Thank you both very much.

The only symptom of all we've read about that she presents with is persisten cough that is loose. Other than that she thrives and her stools are normal.

Any thoughts on that?

 

[anonymous]

another bit of info. both sides of my family are no stranger to bad allergies and asthma though.

 

[Emily65Roses]

Several things. One, a lot of family history is noted as "asthma" or "allergies" when it is in fact undiagnosed CF. A surprising amount of CFers go undiagnosed until adulthood. Also, the further back you go, the more likely it is that people died in your family of CF, and no one ever knew. The further back you go in history, the less technology they had, the more likely it was that they missed possible diagnosises. It's possible your family has asthma and allergies, it's possible your family has CF.

As for a cough, but no stools, that doesn't mean much either. Every CF case is radically different. There are many CFers who have mild lung and mild digestive problems. There are many that have severe lung and severe digestive. There are many that have severe lung and no digestive. And there are many still that have severe digestive and no lung. It's honestly surprising sometimes how much each CFer can differ from the next.

This is not, of course, to get you all bummed out. But I don't want to give you false hope. Normal bowels does prove to be a plus for her, it makes it less textbook. But CF is not out of the question.

 

[anonymous]

No no ... don't worry about bumming me out. I came here to get the facts and that is what I'm getting. Thank you very much for not sugarcoating it. Also, I am going to inquire about the blood test. If she does have it I don't want a false negative on the sweat test. I want to know for sure so I can plan what needs to be done to take care of her.

Also .... congrats on the engagment Emily. Exciting times.

 

[Emily65Roses]

Very good place to come for information, if I do say so myself. Haha. Just a piece of what may be useful trivia. You CAN get a false <b>negative</b> on a sweat test for CF. You CANNOT get a false <b>positive</b>. So it if comes out positive, you've got your answer. If it comes out negative, you may have your answer, you may not. The blood testing, now that they have it, is an excellent route to go.

And thank you. Hehehee. <img src="i/expressions/heart.gif" border="0">

 

[LouLou]

I was a healthy sized baby. It led to 3 miss diagnoses before finally they diagnosed me with CF. I presented with pneumonia twice before the age of 3 and stinky messy diapers. Luckily I came along second because my mom was a seasoned mother at that point and new my diaps weren't normal. You can read my story in by blog. If she does have CF the fact that she is not challenged in the pancreas too much will be very helpful in helping her fight off lung infections. Best wishes and I'll keep her in my prayers that she doesn't have CF.

 

[LouLou]

oh and just wanted to add that I'm still a very healthy size 5'3" and 126 lbs. The fact that your sibling isn't a carrier doesn't mean anything at all unfortunately. Now if it was your mother or father that was tested that would be a whole nother story then your chances would be reduced by 50% ... keep your hopes up remember there's a much better chance your not a carrier. Only 1 in 30 americans of caucasion decent are carriers (statistically speaking).

 

[Debi]

As Emily stated, there are all sorts of combinations. I have heavy lung involvement and no digestive issues - so, I have a loose cough and perfectly normal bowels. The sweat tests for me always came back negative for cf. But, once the genetic blood test became available, it definitely showed I have cf. I would certainly insist on a blood test if the sweat test comes back negative. I hope it will lift your spirits to know I am 54, so please don't feel hopeless if the diagnosis turns out to be cf.

Debi
54 w/cf

 

[anonymous]

Once again, I thank you all for all the info. The info on CF and the especially the tests for CF. You all have encouraged me to know that this won't be the end of the world if this is positive. Please pray for my little girl, Cambria. Like any other parent I just want the best for her.

Thanks again .... Michael (Indiana)

 

[anonymous]

I wanted to add one more thing since I haven't seen it listed. There may actually even still be a chance your sister IS a carrier despite a negative carrier screen. There are well over 1200 mutations that cause cf. Carrier testing usually only covers between 30 and 90 of those genes (which account for roughly 90% of the cases of CF in caucasions.) Carrier screening ONLY tests for the most common mutations. Unless your sister had an extended panel through Quest Diagnostics or testing through Ambry (which is doubtful if it was just a screening during pregnancy), she COULD still be a carrier. And, unfortunately, even those two tests do not have 100% detection rates since there are mutations that are still being discovered. This is part of the reason why CF can be such a hard disease to diagnose for some. And, unfortunately, even geneticists, doctors, and specialists NOT in the CF field often do NOT understand the genetics of cf and will spread inaccurate information. Even really GOOD/GREAT doctors/specialists for their field may not understand CF if it's not their specialty because it is such a complex disease and so difficult to diagnose for some people. Most people are straightforward - positive sweat tests and 2 genes on genetic testing but others fall in the gray area, clearly negative sweat tests with 2 genes, or clearly positive sweat tests with 1 or even no genes found on genetic testing, not to mention those with borderline sweat tests and 1 or no genes. Just very complex for a select few although the majority are starightforward and easy to diagnose.

Good luck with your dd's sweat test!!

 

[julie]

My husband has CF, his brother isn't even a carrier of the CF mutation. So yes, as others have stated it's very possible for one sibling to be a carrier and for the other not to be a carrier. Here's a table on my website about probabilities of inheriting CF, might help youto see a visual: <a target=_blank class=ftalternatingbarlinklarge href="http://www.cysticfibrosismaleinfertility.com/Where_to_begin_carrierTesting.html
">http://www.cysticfibrosismalei...n_carrierTesting.html
</a>
If your sister had only a limited panel CF test (from 35-89 mutations) it's very hard to say, "she is not a carrier of CF" because to date, there are over 1300 KNOWN CF mutations and they find new ones all of the time. Here is a website about a company that does CF testing: <a target=_blank class=ftalternatingbarlinklarge href="http://www.ambrygen.com/">http://www.ambrygen.com/</a> and another one, well it is Quest diagnostics but their website seems to be down right now..

Also, family history really isn't relevant. My husbands family has NO history of anyone with CF. This is the case with a number of others on this forum as well.

Welcome to the site and best of luck with the sweat test. Please keep us updated on what is going on.

 

[Cutecurlz]

38 yr old female w/CF. Yep ya can. I am the oldest kid(38yrs) with CF, my younger sister who is 30(31 in Dec) she don't have CF and isn't a carrier, and my lil brother who is 29(waiting a double lung transplant) he has CF too. So yes one sibling can have CF and NOT be a carrier.